Many altitude measurement devices are known, including skydiving altimeters whose sensing element is an aneroid pressure gauge. Such altimeters typically include a dial whose hour circle is graduated from 0 to 4000 meters altitude. An analysis made by the Applicant of several commercially purchased altimeters revealed a hysteresis. This error of linearity was evidenced by calculating the work of friction forces in the mechanism of such altimeters. The mechanism was therefore set on the descent since the absolute altitude measurement error is lower as altitude decreases. These altimeters were set between 0 and 3000 meters altitude as it had been observed that the measurement error increased above 3000 meters altitude. Thus, the maximum error between 0 and 3000 meters altitude reached 21 meters for one of the altimeters, and 34 meters for another altimeter. It is therefore seen that the skydiving altimeters that were analysed have an error of linearity which leads to a measurement inaccuracy on the order of 1%. Further, given the dispersion of characteristics of aneroid capsules and the manufacturing tolerances with which such altimeters are devised, prior calibration is required. In the case of altimeters of the aforementioned type, this calibration is quite tedious. It is performed manually by a person specially trained for this task and consists in reading the value displayed by the altimeter successively at a pressure equivalent to sea-level pressure, then, for example, at a pressure equivalent to that at 4000 meters altitude, and then again at a pressure equivalent to that at 0 m and so on. Each time, the mechanism is adjusted so that the altitude displayed corresponds to the ambient pressure value. Performing such successive iterations gradually reduces the altimeter measurement error.